These studies are aimed at understanding how the human immune system recognizes and destroys foreign cells. Special emphasis is placed on early antigen nonspecific cytotoxic responses (spontaneous cytotoxicity), which precede specific immune recognition. Both cell mediated and humoral mediated forms of spontaneous cytotoxicity have been examined. We have also purified to homogeneity as new class of immunosuppressive carbohydrate from human pregnancy urine. Finally in a collaborative study we have successfully made human hybridomas from patients with systemic lupus erythematosus.